The Specific Characteristics of Limit Errors in Close Range Photogrammetry

Close-range photogrammetry is to determine the shape and size, of the object,in stead of it's absolute position.Therefore, at first, any translation and rotation of the photogrammetric model of the object caused by whole geodesic, photographic and photogrammetric procedures in close-range photogrammetry could not be considered,in other hand, it is necessary to analyze the all reasons which cause the deformations of the shape and size and to present their corresponding theories and equations. This situation, of course, is very different from the conventional topophotogrammetry. In this paper some specific charateristics of limit errors in close-range photogrammetry are presented in detail,including limit errors for calibration of interior elements for close-range cameras, the limit errors of relative and absolute orientations in close-range photogrammetric procedures, and the limit errors of control works in close range photogrammtry. A theoretical equation of calibration accuracy for close-range camera is given. Relating to 3 examples in this paper, their theoretical accuracy requirement of interior elements of camera change in the scope of ±(0.005~0.480)mm. This discussion permits us to reduce accuracy requirment in calibration for an object with small relief,but the camera platform was located in violent vibration environment. Another theoretical equations were also presented for control works in close-range photogrammetry, among them there is equation of relative RMS of base lines (m_S/S), and the equation RMS of start direction. It was proved that the m_S/S could be equal to the relative RMS of m_ΔX/Δ_X. It was proved as well that the permitting RMS of start direction is much bigger than the consistently using one. Some useful equations of limit errors in close range photogrammery were presented as well.Above mentioned suggestions are perhaps beneficial for increasing efficiency,for reducing production cost.